import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        int[] nums = {2, 7, 11, 15};
        int[] result = twoSum(nums, 9);
        System.out.println(result[0]+":"+result[1]);
    }

    public static int[] twoSum(int[] nums, int target) {
        for(int i=0;i<nums.length;i++){
            for(int j=i+1;j<nums.length;j++){
                if(nums[i] == target-nums[j]){
                    return new int[]{i,j};
                }
            }
        }
        return null;
    }
}
